Some departments are indeed not as affected, and if you are looking for a product owner, a project manager, or sales, numbers don't work against you.
But there are departments where they do, even outside of IT. Accounting are mostly white males, HR are mostly female, etc.
So if you have one policy that is general to the whole company, some departments will have a hard time no matter what.
Case in point, one of my clients has a hard time finding a good dev matching diversity policies, but they have no problem finding analysts. For some reasons, good analyst profiles already are pretty diverse and the team is rocking people from all over Europe and Africa, also achieving gender parity without even trying.
Yet it's the same hiring pipeline, and we are all working in the same office. They are not excluding people, in the office, 10% only are locals! But it doesn't work for some demographics, and the general dumb rule is killing their IT projects.